I implemented the shopping list project and have a question about the cellFrame coordinate system. In the project, in order to locate the coordinate to draw the strikethrough line for purchased items, Tim uses the code
CGFloat middleY = cellFrame.origin.y + cellFrame.size.height / 2;
This works well, but when I started changing the divisor to put the line, say, 1/3 the way up the cell rather than in the middle, I discovered that the cellFrame coordinate system starts at the TOP left, not the BOTTOM left. For example, the code
CGFloat middleY = cellFrame.origin.y; // draws the line at the TOP of the cellFrame CGFloat middleY = cellFrame.origin.y + cellFrame.size.height; // draws the line at the BOTTOM of the cellFrame
I was under the impression that all coordinate origins were in the bottom left. What am I missing here?